Non-Hermitian Computers Need No Complex Numbers

Fuente: arXiv
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Main Author: Zhang, Qi
Format: Preprint
Published: 2026
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author Zhang, Qi
author_facet Zhang, Qi
contents In traditional quantum computing, it has been established that real quantum computation augmented with non-Clifford gates is as powerful as universal quantum computation. Here we investigate this phenomenon in the non-Hermitian setting. We show that a non-Hermitian quantum computer equipped with the real gate set ${H, \text{CCNOT}, G}$, where $G = \operatorname{diag}(g^{-1}, g)$ with $g > 0$ and $g \neq 1$, can solve problems in $\text{P}^{\sharp\text{P}}$ in polynomial time, matching the capability of its universal non-Hermitian counterpart ${H, T, \text{CNOT}, G}$. This demonstrates that non-unitarity, rather than universality, is the essential resource, and that complex numbers are unnecessary.
format Preprint
id arxiv_https___arxiv_org_abs_2605_28152
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Non-Hermitian Computers Need No Complex Numbers
Zhang, Qi
Quantum Physics
In traditional quantum computing, it has been established that real quantum computation augmented with non-Clifford gates is as powerful as universal quantum computation. Here we investigate this phenomenon in the non-Hermitian setting. We show that a non-Hermitian quantum computer equipped with the real gate set ${H, \text{CCNOT}, G}$, where $G = \operatorname{diag}(g^{-1}, g)$ with $g > 0$ and $g \neq 1$, can solve problems in $\text{P}^{\sharp\text{P}}$ in polynomial time, matching the capability of its universal non-Hermitian counterpart ${H, T, \text{CNOT}, G}$. This demonstrates that non-unitarity, rather than universality, is the essential resource, and that complex numbers are unnecessary.
title Non-Hermitian Computers Need No Complex Numbers
topic Quantum Physics
url https://arxiv.org/abs/2605.28152